Tooling that quickly boosts profits

We all want to be more profitable, and one of the easiest ways to accomplish that is by reducing or eliminating machine setup and changeover times. Fortunately, a range of offerings are available to rapidly change a tool configuration. The catch-all category most often used to describe them is quick-change tools.

Some type of quick-change tool is available for every manufacturing process, and all of them can be placed in two categories: workholders and toolholders. They range from simple work stops to complex machine tool probes.

A waterjet machine fixture with the Unilock interface shows the stud that goes into the receiver. All images courtesy C. Tate.

Quick-change workholders are probably the most common if, like me, you consider vises and chucks to be quick-change devices. Chucks and vises are often not sold as quick-change tools, but the devices that can be attached to them are.

Every vise and chuck requires a set of jaws for holding a part, and quick-change jaws are readily available; they are probably the easiest-to-use and lowest-cost quick-change tool available.

Most job shops rely on 3-jaw chucks outfitted with machinable soft jaws to hold their work when turning. For simple jobs, however, it can easily take an hour to find, change and remachine a set of soft jaws. One job changeover per day is equal to 260 hours of set up per year. Because job shops typically recover setup costs, a 50 percent reduction in time means 130 hours of extra revenue.

Standard lathe jaws require a machinist to remove and install two screws per jaw when changing them. Jaws are typically remachined after a change to maintain accuracy. Jaw inserts are available that can be removed and replaced in seconds. Most of these jaws are also highly repeatable, eliminating the need to remachine jaws for most jobs.

The rotary table inside a waterjet machine has the Unilock receiver in the center of the plate. The receiver is pneumatic and operated with the ball valve (shown in the lower, left-hand corner). It takes only 2 minutes to change fixtures with this setup.

It is common, but expensive and inflexible, for any machine shop to make dedicated workholders for milling machines. Shops can eliminate the need for dedicated fixtures by using machinable vise jaws, such as ones from Detroit-based Snap Jaws Manufacturing that can be removed with a quarter turn of a screw. This allows the user to change workholding in less than a minute. Unlike a dedicated fixture, a set of jaws is relatively inexpensive and can be reused for other jobs.

Dedicated workholding is sometimes required when a vise or chuck cannot be configured to efficiently hold a workpiece. Quick-change tools are available to shorten loading and setup times for dedicated fixtures, such as the Ball Lock mounting system from Jergens Inc., Cleveland. This system works by having a machine-mounted baseplate that can accept subplates with fixtures for holding parts. The baseplate has receivers that accept pins, which locate the subplate and provide substantial pull-down force to hold the subplate on the baseplate. Changeover for small fixtures is fast and accurate enough to eliminate the need for fixture alignment.